.lck files are temporary, and if you can't delete it, it would have to be in use, so if you believe the Xerox is at fault, unplug it from the network and delete the file/folder.
Boot into Safe mode and delete it
Use Command Prompt as admin and delete it
Use Process Explorer
I recently set the scan to SMB with the settings below.
Now I need to change directories and delete old ones, but I have no access rights to the DOC.LCK folder created by WC3345.
I don't have permissions with Domain Admin or the scan users. Any help will be appreciated.